1. Field of the Invention
The present invention relates to a fuel cell and, more particularly, to an assembly structure for the fuel cell, in which a cell stack having a plurality of square units of laminated cell elements stacked in a column shape is fastened from both its end faces by fastening means.
2. Description of the Prior Art
Generally speaking, a fuel cell is constructed into a cell stack: by stacking in a column shape both a number of cell elements, each of which is composed of a matrix layer impregnated with an electrolyte, a porous fuel electrode and a porous oxidizer electrode sandwiching the matrix layer inbetween, a plate disposed outside and formed with grooves for supplying fuel gases as reactive gases, and a plate disposed outside and formed with grooves extending at a right angle with respect to the former supply grooves for supplying oxidizing gases, and a number of cooling plates sandwiched between every plural ones of the cell elements for cooling the heat generated when the fuel cell is run; and by fastening the cell elements and the cooling plates in the stacking direction.
In this case, according to the prior art, there has been adopted a structure in which several to several tens of the cell elements are joined in advance to form a unit laminate and in which a plurality of the laminates are stacked to form the cell stack. Only the units having satisfactory characteristics can be assembled into the cell stack by laminating the cell elements in advance into the unit and by testing the characteristics of the units thus laminated before these units are stacked. Thus, it is possible to prevent any bad cell element or elements from being assembled into the cell stack.
Despite of this fact, however, the characteristic tests of the units are conducted under the state in which the units are fastened under a predetermined pressure. As a result, if the units having been tested are released from the fastening pressure when they are to be assembled into the cell stack, there arises a problem that the matrix layers or sealing members are broken so that the electric and thermal resistances are increased. Therefore, it has been desired that the units can be assembled after the tests into the cell stack while being fastened.